1. Field of the Invention
Embodiments of the present invention generally relate to photovoltaic devices and fabrication processes thereof. In particular, embodiments of the present invention relate to apparatus and methods for the fabrication of thin-film photovoltaic devices.
2. Description of the Related Art
Photovoltaic (PV) devices are devices that convert sunlight into direct current (DC) electrical power. A PV device may be classified as monocrystalline, polycrystalline, or thin-film depending on how the device is fabricated.
Monocrystalline PV devices are produced by slicing wafers from a single crystal, high-purity, silicon boule. Polycrystalline PV devices are produced by sawing a cast block of silicon into bars, then wafers. Thin-film PV devices are produced by depositing thin layers of materials, such as amorphous silicon, microcrystalline silicon, or copper indium gallium selenide (CIGS) onto a suitable substrate.
Although monocrystalline and polycrystalline silicon have traditionally produced PV devices with higher efficiencies, the high cost of crystalline silicon wafers has led the industry into increased use and development of thin-film PV devices.
Accordingly, as the production of thin-film PV devices matures, the need for increased process control has developed. This need is driven by both yield and uniformity considerations. Additionally, fast and effective ramp-up of new or duplicated production lines is needed as well.
Therefore, a need exists for apparatus and methods for optimizing processes for the fabrication of thin-film photovoltaic devices.